Wireless Architecture in Support of Voice and Data Communications

ABSTRACT

A wireless access network including a wireless base station configured to, for Iu-CS voice traffic, act as a network controller, by, terminating Iu-b signals from user equipment, and relaying the voice traffic over Iu-CS via an IP sec tunnel. And for data traffic, wireless base station is configured to act as the network controller, by, terminating Iu-b signals from the user equipment, striping IP payload, and sending the data traffic inside IPsec. Further, the wireless access network includes a wireless gateway configured to act as a security gateway for Iu-CS voice traffic, by, establishing the IP sec tunnel with the femtocell base station without the support of a GPRS Tunneling Protocol (GTP) as defined over Iu-PS. Also receiving and forwarding the tunneled Iu-CS voice traffic to a mobile switching center, and for data traffic, encapsulate the IP payload and send it via Gn to GGSN.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 13/371,331 filed 10 Feb. 2012, that is a continuation of U.S. patent application Ser. No. 12/250,947 filed on 14 Oct. 2008 that claims priority from a U.S. Provisional Application 60/979,795, filed 12 Oct. 2007.

FIELD OF THE INVENTION

The present application relates to voice and data communications in wireless networks, and more particularly to the support of efficient data communications in a radio access network with femtocell base stations.

BACKGROUND OF THE INVENTION

Note that the points discussed below may reflect the hindsight gained from the disclosed inventions, and are not necessarily admitted to be prior art. Increasing number of people want to use mobile phones for both voice and data services. They want to access those services wherever they are, including in their home residences. However, to provide full and sufficient mobile coverage is always challenging for the mobile operators, and many times the mobile coverage in the home may be poor. To provide better coverage, the mobile operators need to add more base stations, which may not be economical due to the high cost of the base station and the revenue that it generate in the coverage area.

To solve this problem, the industry has introduced the concept of a femtocell. Originally called an access point base station—a scalable, multi-channel, two-way communication device extending a typical base station by incorporating all of the major components of the telecommunications infrastructure. Application of VoIP techniques allows such a unit to provide voice and data services in the same way as a normal base station, but with the deployment simplicity of a Wi-Fi access point.

A cheap, small capacity femtocell base station can be installed in a subscriber's home. Femtocell base stations provide full 3G base stations with low transmission power and use an already-existing fixed line as the backhaul path, saving the cost from the expensive ATM backhaul. Since it is using the 3G base station technology, a femtocell base station allows the existing handsets to work without any changes, e.g. without the support of Wi-Fi at the handsets. In summary, femtocells extend the mobile coverage to residential homes and replace the expensive backhaul link with cheap broadband connection, without the need to modify the handsets.

In the radio access network, the governing element is an RNC (radio network controller) that is responsible for radio resource management. The RNC connects to a circuit-switched core network through a media gateway (MOW) and to an SGSN (serving GPRS (general packet radio service) support node). The logic connections between the network elements, known as interfaces, are shown in FIG. 1. The interface between the RNC and the circuit switched core network (CS-CN) is called lu-CS and between the RNC and the packet switched core network is called Iu-PS. Other interfaces include lub (between the RNC and the node-B) and Iur (between RNCs in the same network). Iu interfaces carry user traffic (such as voice or data) as well as control information, and lur interface is primarily used for soft handovers.

Since the femtocell device typically contains all the telecommunication elements such as a Node-B, RNC, and GSN with only an Ethernet or broadband connection to the Internet or an intranet, the supporting interfaces need to be encapsulated in IP and transported to suitable entry point in the operator's network.

Several architectures are possible to support femtocell operations, depending on the capability of the femtocell base stations and the corresponding core network node.

Several examples are as follows:

lub over IP: A femtocell base station supports 3G radio base station functionalities and is connected to the radio network control (RNC) node. Iub interface is supported between the femtocell base station and the RNC. This is typically a less open single vendor solution, and usually femtocell base stations and RNCs are bundled.

Iu-CS/Iu-PS over IP: A femtocell base station supports 3G base station and RNC functionalities, and it is connected to the MSC and SGSN in the core network. lu-CS and lu-PS interface is supported between femtocell base station and the MSC (mobile switching center) and SGSN, respectively. This configuration has the advantage of reducing one node from the user plane.

SIP (Session Initiation Protocol) method: SIP provides a signaling and call setup protocol for IP-based communications that can support a superset of the call processing functions and features present in the public switched telephone network. In a SIP based femtocell, all the core network functionalities (including RNC, SGSN, and GGSN (Gateway GPRS Support Node (GGSN)) are collapsed into the femtocell base stations, and the femtocell base station terminates all the Non Access Stratum (NAS) messages.

In an SIP based femtocell architecture, pure IP packets are produced from femtocell base stations and all the services are provided via SIP. This architecture provides the framework for all-IP network and services and is a desirable architecture. However, the femtocell base stations need to provide most functionality support for all the services, in particular, the femtocells are required to perform the voice call control to SIP translation for voice traffic.

Even though these mechanisms extend the coverage to residential homes and replace the expensive backhaul with an IP network, they still utilize the 3G signaling (i.e., lub or lu-CS/Iu-PS) although enwrapped in IP. The non-IP payload transfer over IP is not an efficient way of handling data applications for the femtocell design.

The reuse of existing RAN technologies (and potentially re-use of existing frequency channels) could also create problems, since the additional femtocell transmitters represent a large number of interference sources, potentially resulting in significant operational challenges for existing deployments.

Also femtocell technology typically relies on the Internet for connectivity, which although reduces deployment costs but introduces security risks that generally do not exist in typical cellular systems.

A more efficient and secure way of communication interface is needed for the success deployment of femtocell network architecture.

SUMMARY OF THE INVENTION

The present application discloses new approaches to provide a new architecture for the radio access network that uses the femtocell base stations, to enhance the data handling efficiency in terms of protocol and processing overhead without requiring extra burdens or responsibilities on the femtocell base station.

This new architecture utilizes the functionalities of the Tunnel Terminating Gateway (TTG) defined in interworking WLAN (I-WLAN) with 2G/3G system by 3GPP. By incorporating the TTG functionalities into a gateway called Metro-WSG (Metro-Wireless Service Gateway), the data traffic (i.e. the IP traffic) is carried from the femtocell base station to the Metro-WSG in native IP packets, instead of encapsulated in 3G data, which enhances the efficiency and the performance of the data transport.

Further, because the voice traffic is tunneled through TTG without processing, Metro-WSG does not need to add functionality to support voice traffic. Thus, the disclosed solution re-uses the MSC for user traffic (voice or data).

The present disclosure provides one more step towards the all-IP based femtocell architecture, where both voice and data traffic can be handled efficiently at the femtocell base station. In one preferred embodiment, IP packet is sent via IPsec tunnel from the femtocell base station to the Metro-WSG where the voice traffic can still be handled using traditional 2G/3G methods, the femtocell base station does not need to support 2G/30 call control for SIP conversion, saving a huge workload and overhead from the femtocell base stations.

In another preferred embodiment, the disclosed approach integrates IWLAN architecture into femtocell architecture, enabling the Metro-WSG to serve both IWLAN and femtocell users. This provides flexibility and choices to the operators so that the operators can provide both femtocell and IWLAN services using the same core network node (Metro-WSG) maximizing return on the investment in the deployment.

The disclosed innovations, in various embodiments, provide one or more of at least the following advantages:

allowing mobile operators to extend their 3G coverage to the residential homes, with better data handling efficiency;

providing more value to the mobile operators who already provide IWLAN services with TTG in their networks to support the femtocell architecture for handsets without Wi-Fi capability;

allowing IWLAN operators to provide the femtocell services without a large extra investment since the disclosed approaches re-use the TTG to support femtocell architecture,

benefiting the femtocell base station vendors, since disclosed approaches simplify the femtocell base station implementation by removing the need to support Iu-PS;

supporting both single-mode and dual-mode handsets;

supporting both IWLAN and femtocell architecture at the same node, and

reducing the femtocell base station's development cost and time, which will eventually accelerate the adoption of femtocell architecture in the industry.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed inventions will be described with reference to the accompanying drawings, which show important sample embodiments of the invention and which are incorporated in the specification hereof by reference, wherein:

FIG. 1 schematically shows the femtocell architecture with Metro-WSG.

FIG. 2 shows an example of the protocol stack of a conventional femtocell architecture which supports Iu-PS over IP.

FIG. 3 shows the protocol stack of a preferred embodiment of the proposed architecture.

FIG. 4 shows the protocol stack of a control plane of the disclosed architecture.

DETAILED DESCRIPTION OF SAMPLE EMBODIMENTS

The numerous innovative teachings of the present application will be described with particular reference to presently preferred embodiments (by way of example, and not of limitation).

The preferred embodiment of the disclosed innovations provides architecture for femtocell environment where the voice is handled in the operator's MSC as in lu-CS over IP architecture and the data is handled as simple IP payload, instead of 3G payload. This is accomplished mainly by a set of core network functionalities that provide enhanced tunnel terminating gateway (TTG, as defined in 3GPP IWLAN spec). This set of core network functionalities are implemented at a node called Metro-WSG in this preferred embodiment. FIG. 1 shows the femtocell architecture with Metro-WSG.

In a femtocell architecture, a security gateway is needed since the traffic is sent through a public IP network and the traffic (both data and control) needs to be protected. In general, the security gateway establishes the secure tunnel (i.e. IPsec) with femtocell base station. In the preferred embodiment as shown in FIG. 1, Metro-WSG performs the security gateway role and establishes the IPsec between a femtocell base station and itself as the first step to provide service to the femtocell base station (100).

In the preferred embodiment, the femtocell base station acts as RNC for the voice traffic. Thus, it terminates the Iu-b signaling from the UE and relays the traffic over Iu-CS.

For voice traffic, the Metro-WSG simply acts as security gateway and plays no role in supporting Iu-CS. Therefore, the lu-CS from the femtocell base station is first tunneled inside IPsec between the femtocell base station and the Metro-WSG (101) (see FIG. 1) and then the Metro-WSG simply forwards the Iu-CS traffic to the MSC (102). This approach ensures that the voice services are supported in the same way as 3G voice services, and no further functionalities (e.g. CC to SIP translation, etc.) are needed at the femtocell base station to support voice services.

For the data traffic, the femtocell acts as RNC towards the UE, and terminates the Iu-b signalling from the UE. However, instead of carrying the IP data payload inside Iu-PS, the femtocell base station simply strips the IP payload and sends it inside IPsec, as pure IP payload (103). The Metro-WSG then encapsulates the IP payload to send it over Gn to GGSN (104). In case the Metro-WSG is working in PDG (Packet data gateway) mode, Metro-WSG can also route the traffic directly to the destination PDN, without encapsulating it over Gn. This approach ensures that the IP data payloads are sent without any further encapsulation or treatment from the femtocell base station, and provides a way to support data services, especially broadband data services, efficiently, thus maximizing the usability of the femtocell architecture which uses IP network as a backhaul.

FIG. 2 shows the protocol stack of a conventional femtocell architecture which supports lu-PS over IP. For the simplicity, the security gateway and the SGSN is shown in FIG. 2 as a combined node (201). In case the security gateway is a separate node from the SGSN, the security gateway terminates the IPsec and tunnels the Iu-PS signalling to the SGSN.

In the preferred embodiment, the femtocell base station terminates the radio interface signalling from the UE and relays the payload over lu-PS. To do this, femtocell base station extracts the IP payload first and then re-encapsulates it into GTP-U (202) and sends it over Iu-PS (203). The femtocell needs to support GTP protocol for this architecture.

FIG. 3 shows the user plane protocol stack of a preferred embodiment of the proposed architecture. In the preferred embodiment, the Metro-WSG (301) plays the role of Tunnel Terminating Gateway (TTG). It terminates the IPsec from the femtocell base station and sends the traffic encapsulated in GTP (302) over Gn to GGSN. The protocol stack in FIG. 3 is almost the same as the protocol stack in FIG. 2, except that there is no GTP-U between the femtocell base station and the Metro-WSG, i.e. the Iu-PS is not needed. The femtocell base station in the disclosed inventions only needs to extract the IP payload and sends it to the Metro-WSG over IPsec.

In the disclosed mechanisms, the femtocell base station carries only IP payload, thus relieving the femtocell base station of the burden to support GTP and also providing a more efficient way to handle data packets. This approach reduces the workload burdening the femtocell base station and re-uses the existing functionality of TTG. It is a step further advanced towards the all-IP femtocell architecture.

FIG. 4 shows the protocol stack of a control plane of the disclosed architecture. In the preferred embodiment, the control plane payload is sent to the Metro-WSG inside IPsec, in the same way as data traffic is handled. The Metro-WSG terminates the NAS signaling, however this is transparent to the UE since Metro-WSG is in a way emulating SGSN functionality for NAS signaling termination. The Metro-WSG supports the NAS signaling. SM (session management) is used to create the PDP context towards the GGSN. GMM (GPRS mobility management) is used for moving across femtocell and macro cell. Standards-based inter-SGSN handover is performed when a user is moving across femtocell and macro cell. And from the femtocell base station point of view, it treats control traffic the same way as it treats data traffic.

According to various embodiments, there is provided:

Modifications and Variations of the Invention

As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a tremendous range of applications, and accordingly the scope of patented subject matter is not limited by any of the specific exemplary teachings given. It is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

The claims as filed are intended to be as comprehensive as possible, and no subject matter is intentionally relinquished, dedicated, or abandoned. 

What is claimed is:
 1. A wireless access network, method comprising: via a wireless base station, for Iu-CS voice traffic, acting as a network controller, by, terminating Iu-b signals from user equipment; and relaying the voice traffic over Iu-CS via an IP sec tunnel; and for data traffic, acting as the network controller, by, terminating Iu-b signals from the user equipment; striping IP payload; and sending the data traffic inside IPsec; and via a wireless gateway, for Iu-CS voice traffic, acting as a security gateway, by, establishing the IP sec tunnel with the wireless base station without the support of a GPRS Tunneling Protocol (GTP) as defined over Iu-PS; and receiving and forwarding the tunneled Iu-CS voice traffic to a mobile switching center; and for data traffic, acting as a security gateway, by, encapsulating the IP payload and send it via Gn to GGSN.
 2. The method of claim 1, wherein the wireless base station further, handles voice traffic from a user equipment the same way as 3G voice services and without CC to SIP translation function.
 3. The method of claim 1, wherein the wireless base station further terminates Uu radio interface signaling from the user equipment and strips IP payload to be sent to the gateway directly inside a IPsec, instead of encapsulating it inside a lu-PS and sending it inside IPsec.
 4. The method of claim 1, wherein the wireless gateway further routes the IP payload from the wireless station directly to a destination public data network without encapsulation.
 5. The method of claim 1 wherein, the wireless gateway further routes traffic without encapsulating it over Gn to a destination public data network when working in packet data gateway mode.
 6. A radio access network, comprising: a wireless gateway; and a wireless base station configured to, communicate with at least one user equipment without any modifications to support Wi-Fi at the user equipment; communicate with the wireless gateway; send IP data payloads to the wireless gateway inside a secure tunnel without encapsulation; the wireless gateway, configured to, establish the secure tunnel with the wireless base station; act as a security gateway for Iu-CS voice traffic.
 7. The network of claim 6, wherein the wireless gateway includes TTG (tunnel terminating gateway) functionality to route the payload to GGSN.
 8. The network of claim 6, wherein the wireless base station is further configured to strip IP payload to be sent to the wireless gateway directly inside an IPsec, instead of encapsulating it inside a lu-PS and sending it inside IPsec.
 9. A method for data communication in wireless access network comprising, establishing a secure tunnel IPsec between a wireless base station and a wireless security gateway; transmitting, via the wireless base station, Iu-CS traffic inside the tunnel to the wireless security gateway, forwarding, via the wireless security gateway, the Iu-CS traffic to a mobile switching center; and terminating, via the wireless base station, radio interface signal from user equipment; relaying payload from the radio signal over Iu-PS by, extracting the IP payload; re-encapsulating the IP payload into GTP-U; and sending the IP payload over Iu-PS via the tunnel, to the wireless gateway.
 10. The method of claim 9, wherein the wireless security gateway, upon receipt of the IP payload, is configured to work in Tunnel Terminating Gateway mode and encapsulate the payload to send over Gn interface to GGSN.
 11. The method of claim 9, wherein the wireless security gateway, upon receipt of said IP payload, is configured to work in Packet Data Gateway mode and route the payload directly to destination public data network without encapsulation.
 12. A method of managing a radio access network, comprising: transmitting at least one data payload directly over IPsec, between a femtocell base station and a wireless gateway, wherein the transmitting is without the support of GTP as defined over lu-ps; and handling control traffic in substantially the same way as data traffic via the femtocell base station.
 13. The method of claim 12, further comprising, routing the payload to GGSN, via the wireless gateway, wherein the wireless gateway is configured to use TTG (tunnel terminating gateway) functionality.
 14. The method of claim 12, further comprising, relaying, via the femtocell base station, voice traffic from a user equipment over a Iu-CS interface to the wireless gateway.
 15. The method of claim 12, further comprising, handling, via the femtocell base station, voice traffic from a user equipment the same way as 3G voice services and without CC to SIP translation function.
 16. The method of claim 12, further comprising, forwarding, via the wireless gateway, lu-CS traffic from the femtocell base station to a Mobile Switching Center.
 17. The method of claim 12, further comprising, via the femtocell base station, terminating Uu radio interface signaling from a wireless handset; and stripping IP payload to be sent to the gateway directly inside a IPsec, instead of encapsulating it inside a lu-PS and sending it inside IPsec.
 18. The method of claim 12, further comprising, via the wireless gateway, receiving an IP payload from the femtocell base station; and encapsulating the payload to send a Gn interface to a GGSN.
 19. The method of claim 12, further comprising, via the wireless gateway, routing the IP payload from the femtocell base station directly to a destination public data network without encapsulation. 